diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8f581a15d1b..9749a61b82e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Changed to implementation of `Mesh.unify_cycles` to use the corresponding function of `compas.topology.orientation`.
 * Fixed bug in `compas.topology.orientation.unify_cycles`.
 * Fixed bug in `Mesh.thickened`.
+* Fixed various bugs in `compas.geometry.Quaternion`.
+
 
 ### Removed
 
diff --git a/src/compas/geometry/quaternion.py b/src/compas/geometry/quaternion.py
index 0dd0946099d..687bc54c6c7 100644
--- a/src/compas/geometry/quaternion.py
+++ b/src/compas/geometry/quaternion.py
@@ -159,7 +159,7 @@ def __getitem__(self, key):
             return self.y
         if key == 3:
             return self.z
-        raise KeyError
+        raise KeyError(key)
 
     def __setitem__(self, key, value):
         if key == 0:
@@ -170,9 +170,11 @@ def __setitem__(self, key, value):
             return
         if key == 2:
             self.y = value
+            return
         if key == 3:
             self.z = value
-        raise KeyError
+            return
+        raise KeyError(key)
 
     def __iter__(self):
         return iter(self.wxyz)
@@ -367,7 +369,7 @@ def unitize(self):
         True
 
         """
-        qu = quaternion_unitize(self)
+        qu = quaternion_unitize(list(self))
         self.w, self.x, self.y, self.z = qu
 
     def unitized(self):
@@ -387,7 +389,7 @@ def unitized(self):
         True
 
         """
-        qu = quaternion_unitize(self)
+        qu = quaternion_unitize(list(self))
         return Quaternion(*qu)
 
     def canonize(self):
@@ -408,7 +410,7 @@ def canonize(self):
         Quaternion(0.500, -0.500, -0.500, -0.500)
 
         """
-        qc = quaternion_canonize(self)
+        qc = quaternion_canonize(list(self))
         self.w, self.x, self.y, self.z = qc  # type: ignore
 
     def canonized(self):
@@ -430,7 +432,7 @@ def canonized(self):
         Quaternion(0.500, -0.500, -0.500, -0.500)
 
         """
-        qc = quaternion_canonize(self)
+        qc = quaternion_canonize(list(self))
         return Quaternion(*qc)  # type: ignore
 
     def conjugate(self):
@@ -448,7 +450,7 @@ def conjugate(self):
         Quaternion(1.000, -1.000, -1.000, -1.000)
 
         """
-        qc = quaternion_conjugate(self)
+        qc = quaternion_conjugate(list(self))
         self.w, self.x, self.y, self.z = qc
 
     def conjugated(self):
@@ -469,5 +471,5 @@ def conjugated(self):
         Quaternion(1.000, -1.000, -1.000, -1.000)
 
         """
-        qc = quaternion_conjugate(self)
+        qc = quaternion_conjugate(list(self))
         return Quaternion(*qc)
diff --git a/tests/compas/geometry/test_quaternion.py b/tests/compas/geometry/test_quaternion.py
index ca76d7c40ec..3f3e5646474 100644
--- a/tests/compas/geometry/test_quaternion.py
+++ b/tests/compas/geometry/test_quaternion.py
@@ -5,6 +5,7 @@
 
 from compas.geometry import Quaternion
 from compas.geometry import close
+from compas.geometry import Frame
 
 
 @pytest.mark.parametrize(
@@ -63,22 +64,89 @@ def test_quaternion_data():
         assert Quaternion.validate_data(other.__data__)
 
 
-# =============================================================================
-# Constructors
-# =============================================================================
-
 # =============================================================================
 # Properties and Geometry
 # =============================================================================
 
+
+def test_quaternion_properties():
+    w = 1.0
+    x = 2.0
+    y = 3.0
+    z = 4.0
+
+    quaternion = Quaternion(w, x, y, z)
+
+    assert quaternion.wxyz == [w, x, y, z]
+    assert quaternion.xyzw == [x, y, z, w]
+    assert close(quaternion.norm, 5.4772255)
+    assert quaternion.is_unit is False
+
+    quaternion = Quaternion(0.0, 0.0, 0.0, 1.0)
+    assert quaternion.norm == 1.0
+
+
 # =============================================================================
 # Accessors
 # =============================================================================
 
+
+def test_quaternion_accessors():
+    w = 1.0
+    x = 2.0
+    y = 3.0
+    z = 4.0
+
+    quaternion = Quaternion(w, x, y, z)
+
+    assert quaternion[0] == w
+    assert quaternion[1] == x
+    assert quaternion[2] == y
+    assert quaternion[3] == z
+
+    quaternion[0] = 5.0
+    quaternion[1] = 6.0
+    quaternion[2] = 7.0
+    quaternion[3] = 8.0
+
+    assert quaternion.w == 5.0
+    assert quaternion.x == 6.0
+    assert quaternion.y == 7.0
+    assert quaternion.z == 8.0
+
+
 # =============================================================================
 # Comparison
 # =============================================================================
 
+
+def test_quaternion_comparison():
+    quaternion1 = Quaternion(1.0, 2.0, 3.0, 4.0)
+    quaternion2 = Quaternion(1.0, 2.0, 3.0, 4.0)
+    quaternion3 = Quaternion(5.0, 6.0, 7.0, 8.0)
+
+    assert quaternion1 == quaternion2
+    assert quaternion1 != quaternion3
+
+
 # =============================================================================
-# Other Methods
+# Methods
 # =============================================================================
+
+
+def test_quaternion_other_methods():
+    quaternion = Quaternion(1.0, 2.0, 3.0, 4.0)
+
+    conjugate = quaternion.conjugated()
+    assert conjugate.w == 1.0
+    assert conjugate.x == -2.0
+    assert conjugate.y == -3.0
+    assert conjugate.z == -4.0
+
+    unitized = quaternion.unitized()
+    assert unitized.is_unit
+
+    quaternion = Quaternion.from_frame(Frame.worldZX())
+    canonized = quaternion.canonized()
+
+    assert str(canonized) == str("Quaternion(0.5, -0.5, -0.5, -0.5)")